Piston



Jan. 17, 1950 A. w. ERNEsTUs PISTON Filed Feb. 16, 1946 Patented Jan.17, 1950 UNITED STATES PATENT OFFICE PISTON Application February 16,1946, Serial No. 648,189

1 Claim.

This invention relates to a piston having a heat dam and to a method ofconstructing the heat dam.

1n order to prevent the conduction of excessive heat from the pistoncrown to that part of the piston which contains the piston rings and theskirt, certain types of pistons, particularly those used in highcompression internal combustion engines, may be provided with a heat damon the inside of the piston on or below the piston crown. This locationof the heat dam causes not only considerable difliculty in themanufacture of pistons with a forged crown but also in the machining ofheat dams on the inside of the piston, particularly because the mountingof the trunnions usually leaves very little space for tools to reach theproper heat dam location on the inside of the piston.

The principal object of the present invention is to overcome thediililties in machining a heat dam on the inside of a piston and toprovide a piston with a heat dam where no machining for the heat dam isrequired on the inside of the piston.

Another object is to provide a piston in which conduction ofheat fromcrown to skirt is substantially lessened by employment of heatinsulating material in a groove therebetween.

A preferred embodiment of the invention is illustrated in theaccompanying drawing in which:

Figure 1 is a vertical sectional view of a piston; and

Fig. 2 is a transverse section taken on the line 2-2 of Fig. 1.

The piston illustrated in the drawings is formed of a crown or pistonhead I and skirt 2 welded together at 3.

The crown I is forged with cylindrical iiange I.

The flange 4 has a number of circumferential grooves 5 machined in itsouter surface for receiving piston rings. `The flange 4 also has alarger circumferential groove 8 machined therein Just below the top ofthe piston head. The depth o! groove 6 and its width at the base shouldbe sufflcient to provide the relatively thin connecting web 'I betweenthe top of the piston and its side. The thin web I constitutes a heatdam that prevents excessive iiow of heat from the top of the crown tothe side wall of the piston.

In order to prevent carbon from forming in groove B and at the same timeprevent neutralization of the effect of the heat dam, a low conductivitythin ring member 8 is placed over the mouth of groove 6 substantiallyflush with the outer surface of the piston wall. The member 8, forexample, may be a ring sweated into place or 2 may be a band fastenedmechanically or welded at the meeting edges.

Before the groove 6 is closed it may be filled with sodium or likerelatively heat stable material 9 which is a poor heat conductor andprevents carbon accumulation therein.

The flange I Il extends inwardly of the crown and is radially spacedfrom web 1. Flange I0 is forged in the initial forging of crown I.

The trunnions II are welded to flange I0 as at I2. The bearings I3 ofthe trunnions have horizontal aligned openings therethrough in line withapertures Il which extend radially through the piston wall for passageof a connecting rod, not shown.

The invention eliminates the difficulties encountered, due to theproximity of flange I0 to the web area. in machining the heat dam on theinside and also the bosses of trunnions II.

Various embodiments of the invention may be enayed within the scope ofthe accompanying c The invention is claimed as follows:

A piston for internal combustion engines and the like comprising a crownand a cylindrical skirt-like side wall depending from said crown, saidside wall having a circumferential groove in the outer surface of saidside wall and spaced downwardly from the periphery of said crown. saidgroove constituting a heat dam between the periphery of said crown andsaid depending side wall, and a thin closure ring of material of lowheat conductivity inset into said side wall and extending across themouth of said groove and spaced downward from the periphery' of saidcrown, said thin closure ring being protected by the periphery of saidcrown against direct exposure to hot products of combustion above saidCX'OWD..

ADOLPH W. ERNESTUB.

REFERENCES CITED The following references are of record in the ille ofthis patent:

UNITED STATES PATENTS Number Name Date 1,407,202 Kubler l'eixo.` 21,1922 1,494,483 Howe May 20, i924 50 1,584,265 Williams May 11, 19201,678,957 Philipp July $1, 1928 1,831,583 Weiss Nov. 10, 1981 FOREIGNPATENTS 55 Number Country Date 28,593 Great Britain oi 1911 325,194Great Britain Feb.. 8, 1030 358.958 Great Britain Apr. 10, 1030

